Hi:

The fitdistrplus package from CRAN may be useful. I tried it on your data
and the lognormal seemed to fit well, apart from the outlier. I just
followed the vignette that accompanies the package.

library(fitdistplus)

plotdist(NOEccu)                             # ecdf
descdist(NOEccu, boot = 1000)      # Cullen-Frey graph based on 1000
bootstrap samples

# The Cullen-Frey graph suggests that the distribution is somewhere between
a Gamma and lognormal

# Weibull
N1w <- fitdist(NOEccu, 'weibull')
# Warning messages:
# 1: In dweibull(x, shape, scale, log) : NaNs produced
# 2: In dweibull(x, shape, scale, log) : NaNs produced
plot(N1w)
summary(N1w)

# Gamma
N1g <- fitdist(NOEccu, 'gamma')
# Warning messages:
# 1: In dgamma(x, shape, scale, log) : NaNs produced
# 2: In dgamma(x, shape, scale, log) : NaNs produced
# 3: In dgamma(x, shape, scale, log) : NaNs produced
# 4: In dgamma(x, shape, scale, log) : NaNs produced
plot(N1g)
summary(N1g)

# Lognormal
N1l <- fitdist(NOEccu, 'lnorm')
plot(N1l)
summary(N1l)

Try it out and see if it suits your needs.

HTH,
Dennis

On Tue, Mar 15, 2011 at 9:00 AM, Lathouri, Maria <
m.lathouri06@imperial.ac.uk> wrote:

> Dear all,
>
> I need to plot an cumulative distribution plot of a variable and then to
> fit a distribution to that, probably a weibull or lognormal.
>
> I have plotted the ecdf as
> > plot(ecdf(x))
>
> but I haven't managed to fit the distribution. I have as well attached the
> data.
>
> I would appreciate if you could help me on that.
>
> Thank you.
>
> Kind regards
> Maria
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>

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